Check log output in thread affinity tests

Check log output in thread affinity tests

Use the ability to redirect the logging to actually check that the
correct warnings get produced for the tests.  For now, most expected
texts are partially duplicated in each test that produces them, but
these can be centralized if it becomes a problem.

All regular output from thread affinity setting now goes through mdlog,
except for one to stderr.

Change-Id: I603e838693b6593d116fb2597eda7f1bf97c9454